Spinal Cord and Spinal Nerves Flashcards
Define spinal nerve and cauda equina
- 31 pairs in and out, part of the PNS for taking messages to anf from spinal cord
- mixed, caring both sencory and motor infor
- Cauda Equina to go inferior to spinal nerve, resembles horse tail
Describe the overall functions of the spinal cord
carries messages to and from the brain
-spinal reflexes
Describe the location of the spinal cord
-in the vertebral foramen, formen magnum to about L2 (spinal cord finishes developing before bones of spine do)
Describe the significance of the two spinal cord enlargments
Arms & legs nerves entering & exiting spinal cord
Name the protective covering of the CNS (general and specific)
-Meninges- around the brain and spinal cord
1 dura mater- the outermost membrane, dense
2 Archnoid- middle spiderlike layer (location of CSF)
3 Pia mater- innermost delicate layer (adheared to spinal cord.
Describe the location of the cerebrospinal fluid (CSF)
Subarachnoid space
name the space and location where anesthetics are given
- given in the dura mater, in the epidural space
- they are given at L2 or below to reduce risk of hitting spinal cord
Describe the parts of the gray matter of the spinal cord
- no myolin-it would contain neuron cell bodies, and unmyelinated neurons.
- located in the center of the spinal cord (central Canal)
- contains CSF
- Posterior (dorsal) horns=sensory pathway
- anterior (ventral) horns=motor pathways
Describe the parts of the white matter of the spinal cord
- myolin present
- The lateral, dorsal (posterior) and ventral (anterior) columns. (based on location)
Describe the function of the ascending and descending tracts
- with in the white matter=
- Ascending=sensory (towards brain)
- Descending tracts=Motor (away from brain) U.M.N- upper motor neurons (cns)
reflex
fast-involuntary-repeatable
-reaction to a stimulus
Spinal reflex
-If it involves the spinal cord it is a spinal reflex.
somatic reflex
-A somatic reflex terminates in skeletal muscle
autonomic reflex
-terminates in smooth muscle, cardiac muscle and glands.
Describe the pathways of a generalized reflex arc
- receptor (dendrite that interperates stimulus)
- sensory (afferent) neuron
- spinal cord (CNS)
- motor (efferent) neuron
- Effector (skeletal muscle)
Monosynaptic Reflex
- faster
- the pateller reflex, ipsilateral
Polysynaptic Reflex
- has more than one synpase in the spinal cord
- thus synapsing on interneurons or association neurons before synapsing on the motor neuron.
- slower
ipsilateral Reflex vs Contralateral Reflex
-if they stay ipsilateral may describe the withdrawal reflex and if they go contralateral may describe the crossed extensor reflex.
Pateller reflex
is monosynaptic and ipsilateral
If you hit the patellar tendon, you stretch the quad. muscle and stimulate the stretch receptor. It is an ipsilateral monosynaptic reflex ending with the quad. muscle contracting, thus extending the knee.
Withdraw reflex
ipsilateral, to pull away from the hot heat with out having to think about it
the crossed-extensor reflex
- contralateral
- sends message to stand on other foot so you dont fall
Describe a spinal nerve; include the roots and which roots carry motor/sensory impulses
- 31 pairs
- dorsal and ventral roots are mixed with sensory and motor pathways
Define Ramus
- dorsal rami are smaller
- ventral rami are larger
- branching of the spinal nerve onve it emerges from the intervertebral foramen it branches into a dorsal ramus (branch) going toward your back and a ventral ramus going everywhere else in your body, including limbs and viscera.
- The rami are mixed
Define plexus
- a network of adjacent spinal nerves
Name and locate the 4 main plexus
- cervical= c1-c4/5
- brachial= c5-t1
- Lumbar=t12-l4
- Sacral= L4-S4
Radial Nerve
- Brachial plexus innervates pectoral limb extensors
- all extensors of the arm
Ulnar Nerve
-Brachial plexus innervates distal medial flexors (e.g. flexor carpi ulnaris)
Musculocutaneous Nerve
-Brachial plexus innervates elbow flexors (e.g. biceps brachii)
Median Nerve
-Brachial plexus innervates distal lateral flexors (e.g. flexor carpi radialis)
Femoral Nerve
-Lumbar plexus innervates hip flexors and knee extensors (e.g. quadriceps)
Sciatic Nerve
-Sacral plexus innervates knee flexors (hamstrings) as well as all distal to your knee.
Phrenic Nerve
-Cervical plexus innervates your diaphragm and needed to breathe!
